Users are increasingly turning to content in electronic form, including items offered for sale through various electronic channels. When a user searches or browses for content, such as items offered for sale through an electronic marketplace, relevance information is generally utilized to determine which content to display, as well as the order in which to display that content. For items available through an electronic marketplace, performance metrics such as likelihood of a view or purchase can be used for such ranking and determinations as well. While performance data can be determined by analyzing the actions of customer with respect to instances of displayed content, the performance data will be impacted at least in part by the position at which the content is displayed. For example, items at the top of the list might be more likely to be selected than items at the bottom of a list, and items towards the right of the display in at least some cultures may be less likely to be selected than items towards the center or left of the display. While this bias can be eliminated by displaying the same content multiple times at various different locations and comparing the relative performance, there often will not be the opportunity to collect enough data for accurate determinations of performance bias. Further, for content such as search results where items are ranked by relevance there might be little ability to re-rank or reposition the items of content for reasons separate from relevance.